2 * IP Payload Compression Protocol (IPComp) - RFC3173.
4 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the Free
8 * Software Foundation; either version 2 of the License, or (at your option)
12 * - Tunable compression parameters.
13 * - Compression stats.
14 * - Adaptive compression.
16 #include <linux/config.h>
17 #include <linux/module.h>
18 #include <asm/scatterlist.h>
19 #include <asm/semaphore.h>
20 #include <linux/crypto.h>
21 #include <linux/pfkeyv2.h>
22 #include <linux/percpu.h>
23 #include <linux/smp.h>
24 #include <linux/list.h>
25 #include <linux/vmalloc.h>
26 #include <linux/rtnetlink.h>
27 #include <linux/mutex.h>
31 #include <net/ipcomp.h>
32 #include <net/protocol.h>
35 struct list_head list;
36 struct crypto_tfm **tfms;
40 static DEFINE_MUTEX(ipcomp_resource_mutex);
41 static void **ipcomp_scratches;
42 static int ipcomp_scratch_users;
43 static LIST_HEAD(ipcomp_tfms_list);
45 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
49 struct ipcomp_data *ipcd = x->data;
51 struct crypto_tfm *tfm;
55 dlen = IPCOMP_SCRATCH_SIZE;
59 scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
60 tfm = *per_cpu_ptr(ipcd->tfms, cpu);
62 err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
66 if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
71 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
75 skb_put(skb, dlen - plen);
76 memcpy(skb->data, scratch, dlen);
78 iph->tot_len = htons(dlen + iph->ihl * 4);
84 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
95 if (skb_linearize_cow(skb))
98 skb->ip_summed = CHECKSUM_NONE;
100 /* Remove ipcomp header and decompress original payload */
102 memcpy(&tmp_iph, iph, iph->ihl * 4);
103 nexthdr = *(u8 *)skb->data;
104 skb_pull(skb, sizeof(struct ip_comp_hdr));
105 skb->nh.raw += sizeof(struct ip_comp_hdr);
106 memcpy(skb->nh.raw, &tmp_iph, tmp_iph.iph.ihl * 4);
108 iph->tot_len = htons(ntohs(iph->tot_len) - sizeof(struct ip_comp_hdr));
109 iph->protocol = nexthdr;
110 skb->h.raw = skb->data;
111 err = ipcomp_decompress(x, skb);
117 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
119 int err, plen, dlen, ihlen;
120 struct iphdr *iph = skb->nh.iph;
121 struct ipcomp_data *ipcd = x->data;
123 struct crypto_tfm *tfm;
126 ihlen = iph->ihl * 4;
127 plen = skb->len - ihlen;
128 dlen = IPCOMP_SCRATCH_SIZE;
129 start = skb->data + ihlen;
132 scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
133 tfm = *per_cpu_ptr(ipcd->tfms, cpu);
135 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
139 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
144 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
147 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
155 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
159 struct ip_comp_hdr *ipch;
160 struct ipcomp_data *ipcd = x->data;
164 iph->tot_len = htons(skb->len);
165 hdr_len = iph->ihl * 4;
166 if ((skb->len - hdr_len) < ipcd->threshold) {
167 /* Don't bother compressing */
171 if (skb_linearize_cow(skb))
174 err = ipcomp_compress(x, skb);
181 /* Install ipcomp header, convert into ipcomp datagram. */
182 iph->tot_len = htons(skb->len);
183 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
184 ipch->nexthdr = iph->protocol;
186 ipch->cpi = htons((u16 )ntohl(x->id.spi));
187 iph->protocol = IPPROTO_COMP;
197 static void ipcomp4_err(struct sk_buff *skb, u32 info)
200 struct iphdr *iph = (struct iphdr *)skb->data;
201 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
202 struct xfrm_state *x;
204 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
205 skb->h.icmph->code != ICMP_FRAG_NEEDED)
208 spi = htonl(ntohs(ipch->cpi));
209 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
210 spi, IPPROTO_COMP, AF_INET);
213 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
214 spi, NIPQUAD(iph->daddr));
218 /* We always hold one tunnel user reference to indicate a tunnel */
219 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
221 struct xfrm_state *t;
223 t = xfrm_state_alloc();
227 t->id.proto = IPPROTO_IPIP;
228 t->id.spi = x->props.saddr.a4;
229 t->id.daddr.a4 = x->id.daddr.a4;
230 memcpy(&t->sel, &x->sel, sizeof(t->sel));
231 t->props.family = AF_INET;
233 t->props.saddr.a4 = x->props.saddr.a4;
234 t->props.flags = x->props.flags;
236 if (xfrm_init_state(t))
239 atomic_set(&t->tunnel_users, 1);
244 t->km.state = XFRM_STATE_DEAD;
251 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
252 * always incremented on success.
254 static int ipcomp_tunnel_attach(struct xfrm_state *x)
257 struct xfrm_state *t;
259 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
260 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
262 t = ipcomp_tunnel_create(x);
267 xfrm_state_insert(t);
271 atomic_inc(&t->tunnel_users);
276 static void ipcomp_free_scratches(void)
281 if (--ipcomp_scratch_users)
284 scratches = ipcomp_scratches;
288 for_each_possible_cpu(i)
289 vfree(*per_cpu_ptr(scratches, i));
291 free_percpu(scratches);
294 static void **ipcomp_alloc_scratches(void)
299 if (ipcomp_scratch_users++)
300 return ipcomp_scratches;
302 scratches = alloc_percpu(void *);
306 ipcomp_scratches = scratches;
308 for_each_possible_cpu(i) {
309 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
312 *per_cpu_ptr(scratches, i) = scratch;
318 static void ipcomp_free_tfms(struct crypto_tfm **tfms)
320 struct ipcomp_tfms *pos;
323 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
324 if (pos->tfms == tfms)
333 list_del(&pos->list);
339 for_each_possible_cpu(cpu) {
340 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
341 crypto_free_tfm(tfm);
346 static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name)
348 struct ipcomp_tfms *pos;
349 struct crypto_tfm **tfms;
352 /* This can be any valid CPU ID so we don't need locking. */
353 cpu = raw_smp_processor_id();
355 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
356 struct crypto_tfm *tfm;
359 tfm = *per_cpu_ptr(tfms, cpu);
361 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
367 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
372 INIT_LIST_HEAD(&pos->list);
373 list_add(&pos->list, &ipcomp_tfms_list);
375 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
379 for_each_possible_cpu(cpu) {
380 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
383 *per_cpu_ptr(tfms, cpu) = tfm;
389 ipcomp_free_tfms(tfms);
393 static void ipcomp_free_data(struct ipcomp_data *ipcd)
396 ipcomp_free_tfms(ipcd->tfms);
397 ipcomp_free_scratches();
400 static void ipcomp_destroy(struct xfrm_state *x)
402 struct ipcomp_data *ipcd = x->data;
405 xfrm_state_delete_tunnel(x);
406 mutex_lock(&ipcomp_resource_mutex);
407 ipcomp_free_data(ipcd);
408 mutex_unlock(&ipcomp_resource_mutex);
412 static int ipcomp_init_state(struct xfrm_state *x)
415 struct ipcomp_data *ipcd;
416 struct xfrm_algo_desc *calg_desc;
426 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
430 memset(ipcd, 0, sizeof(*ipcd));
431 x->props.header_len = 0;
433 x->props.header_len += sizeof(struct iphdr);
435 mutex_lock(&ipcomp_resource_mutex);
436 if (!ipcomp_alloc_scratches())
439 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
442 mutex_unlock(&ipcomp_resource_mutex);
445 err = ipcomp_tunnel_attach(x);
450 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
452 ipcd->threshold = calg_desc->uinfo.comp.threshold;
459 mutex_lock(&ipcomp_resource_mutex);
461 ipcomp_free_data(ipcd);
462 mutex_unlock(&ipcomp_resource_mutex);
467 static struct xfrm_type ipcomp_type = {
468 .description = "IPCOMP4",
469 .owner = THIS_MODULE,
470 .proto = IPPROTO_COMP,
471 .init_state = ipcomp_init_state,
472 .destructor = ipcomp_destroy,
473 .input = ipcomp_input,
474 .output = ipcomp_output
477 static struct net_protocol ipcomp4_protocol = {
478 .handler = xfrm4_rcv,
479 .err_handler = ipcomp4_err,
483 static int __init ipcomp4_init(void)
485 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
486 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
489 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
490 printk(KERN_INFO "ipcomp init: can't add protocol\n");
491 xfrm_unregister_type(&ipcomp_type, AF_INET);
497 static void __exit ipcomp4_fini(void)
499 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
500 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
501 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
502 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
505 module_init(ipcomp4_init);
506 module_exit(ipcomp4_fini);
508 MODULE_LICENSE("GPL");
509 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
510 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");